The operational frequency of oscillators is limited by the properties of transistors used and the technology adopted for their implimentation. Thus, for example, implimentations based upon conventional 3-micron size geometry, silicon material, bipolar technology are limited to operational frequencies at most just below to within the lower extreme of S-band (ie. the band 2-4 GH.sub.Z) operation. Hitherto, advance beyond this limit requires either considerable circuit complexity and high component count, or, resort to alternative and expensive advanced technologies, at present in their infancy, ie. smaller geometry and/or faster (ie. higher electron mobility semiconductor--eg. gallium-arsenide) material technologies.
It is known to employ oscillators in a dual purpose role in the construction of tuning circuits--ie. both as a local oscillator source and as a mixer. Applications here likewise are restricted by the frequency limit of the oscillator adopted.
It is of particular note that C-band transmission is specified as an International Standard for Satellite communications. There is an urgent need for oscillators and mixer-oscillators for this application, devices that can be produced with minimal complexity, at low cost, and that can be implimented using well-established and reliable process technology.